(i) To examine the incidence of new onset treated diabetes in patients treated with different types of statins and (ii) the relationship between the duration and dose of statins and the subsequent development of new onset treated diabetes.METHODS
A retrospective cohort study was performed using the Irish Health Services Executive Primary Care Reimbursement Services national pharmacy claims database. Individuals who received any medicines were identified from January 2001 to January 2009 (n = 1 235 671). Patients newly treated with statins from 1 January 2002 to 31 December 2007 were identified (n = 239 628). Cases were identified as individuals newly treated with antidiabetic medication (n = 38 503). Adjusted hazards ratios (HR) with 95% confidence intervals (CI) were calculated to examine the association between statins (any vs. none) and time to new onset treated diabetes using Cox proportional hazard regression. The dose and duration response relationship between statins and new onset treated diabetes was examined using restricted spline functions to assess the linearity of the relationship.RESULTS
Statin use was associated with an increased risk of new onset treated diabetes (HR = 1.18, 95% CI 1.15, 1.22). Increased risk of new onset treated diabetes was found with rosuvastatin (HR = 1.41, 95% CI 1.31, 1.52), atorvastatin (HR = 1.23, 95% CI 1.19, 1.27) and simvastatin (HR = 1.15, 95% CI 1.05, 1.25). There were statistically significant overall dose and duration effects for all statins, excepting fluvastatin, which only demonstrated a duration effect.CONCLUSION
An increased risk of new onset treated diabetes was found in those treated with statins showing significant duration and dose effect. Further study is required to confirm this association.